Increasing intracellular magnesium levels with the 31-amino acid MgtS protein.

Synthesis of the 31-amino acid, inner membrane protein MgtS (formerly denoted YneM) is induced by very low Mg in a PhoPQ-dependent manner in Here we report that MgtS acts to increase intracellular Mg levels and maintain cell integrity upon Mg depletion. Upon development of a functional tagged derivative of MgtS, we found that MgtS interacts with MgtA to increase the levels of this P-type ATPase Mg transporter under Mg-limiting conditions. Correspondingly, the effects of MgtS upon Mg limitation are lost in a ∆ mutant, and MgtA overexpression can suppress the ∆ phenotype. MgtS stabilization of MgtA provides an additional layer of regulation of this tightly controlled Mg transporter and adds to the list of small proteins that regulate inner membrane transporters.